Five key areas that will be of interest to Irish rugby fans, and more importantly to head coach Joe Schmidt as overwhelming favourites Ireland host Fiji at the Aviva Stadium tomorrow (kick-off 5.30pm).

Kearney's competition

Ever since the 2015 World Cup quarter-final defeat to Argentina where the lack of strength in depth behind the starting XV was cruelly exposed, Joe Schmidt has been building a squad where competition is rife.

One possible exception to that is at full-back, exacerbated by the omission of Simon Zebo.

Rob Kearney returned to the fold against South Africa, and admitted himself afterwards that his preparation "wasn't ideal" and injury woes have meant restricted game time over the past couple of seasons.

The 31-year-old has been a mainstay of Schmidt teams at provincial and international level when fit, but where his main competition for the 15 jersey comes from is a question on the lips of many supporters.

The 77-cap international still has plenty to offer Ireland, but even former team-mate and close ally Brian O’Driscoll suggested last week that Kearney would benefit from someone breathing down his neck for selection.

Schmidt has opted for Andrew Conway on Saturday, one of only two survivors from South Africa and his broken field running, aerial ability and defensive nous should serve him well as he switches from the wing. It is another chance to stake a claim, though the Ireland head coach has other options available to him going forward.

Tiernan O’Halloran has had fleeting moments at Test level and continues to shine for Connacht, while Joey Carbery’s versatility could see him as the likely pretender. More of which anon.

For now, it's Conway's opportunity to apply pressure on the 2012 European Player of the Year.

Midfield experimentation

Uncapped Chris Farrell and Stuart McCloskey is the centre partnership against Fiji

What's certain is that a fit Robbie Henshaw starts for Ireland. What's less so is which centre slot he occupies, and more importantly, who lines up alongside him.

The Leinster man thrived at 13 against South Africa - admittedly as did most of his team-mates on the day - and it is the position many observers believe is the one that utilises his strengths to the maximium.

A brilliant defensive reader, some of the passes Henshaw slipped to team-mates against the Springboks and eye for space showed that his attacking instincts, at times curbed at 12, will be a huge boon against tighter defences.

Garry Ringrose has shown enough sparkle at Test level to indicate he too is a viable successor to the Brian O'Driscoll throne. Currently out injured, it is an intriguing selection dilemma when you consider Jared Payne is also sidelined.

Bundee Aki looked right at home on his debut, and now Schmidt is looking to the next batch of contenders against Saturday.

Stuart McCloskey has had to wait 18 months for his second cap, and will be partnered by former Ulster team-mate Chris Farrell on his debut.

McCloskey impressed with a bustling performance in Twickenham, but a litany of injuries have seriously curtailed his progress. Question marks over his ability to vary his game in attack other than a route one approach still remain, but has shown for Ulster time and time again his ability to get over the gain line.

Farrell has been rewarded for a fine start to his Munster career and will be hoping to unlock the Fijian defence with his range of passing.

Ireland won't be wanting in the physical stakes, and Bernard Jackman believes there is enough brawn to match the ballast of the midfield partnership.

Marmion's rare chance to shine from the off

Nestled behind one of the most complete scrum-halves in the game in Conor Murray, Kieran Marmion knows chances to impress simply must be taken.

In the three years since he made his Test bow against Argentina, just four of his 17 caps have come as a starter. Of those four starts, only one of those came in the Six Nations (albeit the slam-buster against England earlier this year) when he deputised for the injured Murray

He may not offer the same physique, defensive solidity and perhaps speed of passing as the Munster man, but the 25-year-old brings tempo, a threat around the fringes and the eye for a break, all noticeable after his introduction against South Africa last weekend. 

The score was 17-3 when he was called into the action and played a key part in the late three-try flurry.

Despite such few starts, Marmion now finds himself as one of the leaders in the team, as only Jack McGrath and Devin Toner have more caps in Saturday's team.

Fiji could be the platform to provide more evidence of his ability to control matters and marshal his troops around the field for an extended period of time.

Lions loosehead in, two-time Lion on the bench

The performance of Cian Healy last Saturday was a throw-back to a time when the Leinster man was in his pomp and up there with the best in the business.

Injuries have plagued him in recent seasons, so much so that he seriously considered quitting the game, but the 30-year-old has diligently worked his way back and the trimmed down physique is clear for all to see.

The 2013 Lion however is in a huge battle with 2017 Lion Jack McGrath at loosehead, who returns to the starting line-up after missing the destruction of the Springboks after limited training following a hip issue earlier in the week.

After conceding 15 penalties against Italy last weekend, McGrath will be looking to put the squeeze on Fiji in the scrum alongside Rob Herring and Andrew Porter, who both make their first starts for their country. 

The 28-year-old is coming into the prime of his career and demonstrated against the All Blacks that he is more than capable of holding his own against any loosehead in the Test arena.

Dave Kilcoyne, another impressive operator last weekend in open play and in the scrum, drops out of the match-day 23, while the luckless James Cronin faces another spell on the sidelines following a calf injury suffered against the Barbarians last week.

All in all, a pretty healthy scenario for the head coach.

Joey in demand

His international career has spanned a grand total of 134 minutes and includes five wins from five, most notably a Test debut victory over the All Blacks in Chicago, but already Joey Carbery looks set to become an integral part of Joe Schmidt's squad. 

The 22-year-old's versatility, combined with extenuating circumstances, means his importance cannot be understated and tomorrow he steps into Johnny Sexton's shoes as part of a new half-back pairing. 

With Paddy Jackson facing trial in January next year and currently relived his his rugby duties and Ian Madigan based in the UK, Carbery is the number one back-up at 10, a point reinforced by Skills and Defence coach Richie Murphy earlier this week.

He nailed two conversions against the Springboks (one from the touchline), all the more impressive given they were his only kicks of the season thus far, while his cross-field kick for Darren Sweetnam was further illustration of his natural attacking instincts and ability to play what is in front of him.

Having worn 15 for Leinster this season, and with Simon Zebo's omission from the Ireland squad, he is also cover at full-back should his services be required.

Irish management have publicly stated that they want the prodigious talent to focus his attentions of the demanding role at out-half, but events may conspire that the New Zealand-born out-half may get to showcase his talents from further backfield.

Fiji enjoyed just 36pc possession in the 19-10 defeat to Italy last weekend, so Carbery should expect to see plenty of front-foot ball, and the chance to build-up a greater understanding with Marmion at half-back could prove highly valuable at later, more important dates.

Live coverage of Ireland v Fiji begins on Saturday on RTÉ 2 television and RTÉ Player at 4.30. Live commentary is on RTÉ Radio 1’s Saturday Sport, which starts at 2.45, and you can follow all of the build-up and action on our live blog online at rte.ie/sport and on the News Now app.